Industrial activity in China has slowed so quickly that demand for cobalt has ground to a halt, according to one of the biggest cobalt miners in the Democratic Republic of Congo, the world’s largest source of the metal.

Camec, the London-listed junior miner, last week mothballed its Mukondo mine, one of the world’s richest cobalt mines, saying it might resume production in early 2009 if prices recover. “It is almost as if there is a buyers’ strike,” said Andrew Groves, chief executive of Camec, referring to Chinese buyers who were buying record quantities of the metal six months ago and sending it to China’s factories to be processed into batteries, propeller blades, magnets and chemicals, among a range of applications so varied that cobalt demand can be seen as a rough proxy of industrial activity.